AR_final file_2018-19

= 0.77 D. Corresponding to each component, the energy levels can be classified into two sets. For each of the six sets, using the spectroscopic data of 2-aminoethanol, we have calculated energies of 150 rotational levels in the ground vibrational state and ground electronic state. For rotational transitions, we have calculated the line intensities and Einstein A -coefficients. For each set, using the Einstein A - coefficients and scaled values of the collisional rate coefficients, we have solved a set of 150 statistical equilibrium equations coupled with the equations of radiative transfer. In the model, there is cosmic microwave background corresponding to a temper- ature of 2.73 K. Brightness temperatures of all the b -type and c -type transitions are found nearly equal to the background temperature. Eight a -type tran- sitions are found to show the anomalous absorp- tion. These transition may play important role for the identification of 2-aminoethanol in a cosmic ob- ject. This work has been done in collaboration with Monika Sharma, and Suresh Chandra. Suggestion for search of silanone (H 2 SiO) in inter- stellar medium Thirteen silicon bearing molecules are detected in the cosmic objects. Carbon (C) and silicon (Si) el- ements have similar chemical properties, and the formaldehyde (H 2 CO) is identified in a large num- ber of cosmic objects. Hence, there is a possibil- ity of Silanone (H 2 SiO) being present in the ISM. For each of the ortho and para species of H 2 SiO, we have calculated energies of 100 lower rotational levels (up to 284 cm − 1 ) and the Einstein coeffi- cients for radiative transitions between the levels. We have solved a set of 100 statistical equilibrium equations coupled with the equations of radiative transfer for each specie, where the collisional rate coefficients are taken from a scaling law. For the ortho-H 2 SiO, five transitions, 1 10 − 1 11 , 2 11 − 2 12 , 3 12 − 3 13 , 4 13 − 4 14 , and 5 14 − 5 15 are found to show the anomalous absorption, and one transition 2 12 − 1 11 is found to show the emission feature. For the para-H 2 SiO, four transitions, 1 01 − 0 00 , 2 02 − 1 01 , 6 60 − 5 14 , and 6 61 − 5 42 are found to show the emission feature. These lines may help in the identification of H 2 SiO in a cosmic object, e.g. , in IRC+10216. This work has been done in collab- oration with Monika Sharma, and Suresh Chandra. Ranjan Sharma A family of solutions to the EinsteinMaxwell sys- tem of equations describing relativistic charged fluid spheres We present a formalism to generate a family of in- terior solutions to the EinsteinMaxwell system of equations for a spherically symmetric relativistic charged fluid sphere matched to the exterior Reiss- nerNordstrm spacetime. By reducing the Einstein- Maxwell system to a recurrence relation with vari- able rational coefficients, we show that it is pos- sible to obtain closed-form solutions for a specific range of model parameters. A large class of solu- tions obtained previously are shown to be contained in this general class of solutions. We also analyse the physical viability of the new class of solutions. This work has been done in collaboration with K. Komathira. Gyan Prakash Singh Thermodynamical and observational aspects of cos- mological model with linear equation of state A cosmological model with linear equation of state in the framework of general relativity is studied. We explore the thermodynamical aspects of the cosmological model with equilibrium description. In particular, we discuss the validity of general- ized second law of thermodynamics for resulting cosmologies. General conditions for this model to satisfy the slow roll conditions for inflation are dis- cussed. This work has been done in collaboration with Nikhil Hulke and Ashutosh Singh. Cosmological study of particle creation in higher derivative theory we have presented accelerated expanding cosmo- logical models with particle creation in flat FRW background within the framework of higher deriva- tive theory. In order to explore the role of particle creation on dynamical parameters, we have consid- ered hybrid, intermediate and emergent forms of scale factor. Further, we have considered the well accepted values of free parameters to explore the possibility of transition from a decelerated to ac- celerated period of expansion based on deceleration parameter and effective equation of state. Finally, the effect on statefinder parameters { r, s } , measur- ing the deviation of the considered models from the concordance model have also been discussed. This ( 214 )